Low-gas permeability coal seam weakening and permeability increasing method combining presplitting and high-pressure water injection

Abstract

The invention discloses a low-gas permeability coal seam weakening and permeability increasing method combining presplitting and high-pressure water injection. The method includes: using a drilling machine to construct a plurality of coal seam weakening and permeability increasing units to a working face gateway pre-exploiting coal seam side, presetting a corresponding presplitting device in one coal seam weakening and permeability increasing unit which comprises three drilled holes, detonating the presplitting device and then injecting high-pressure water into the coal seam weakening and permeability increasing unit, and stopping the water injection when water injection pressure drops suddenly, the corresponding dropped pressure is kept unchanged and stable pressure water flows out of the coal seam weakening and permeability increasing unit so as to complete the weakening and permeability increasing of the coal seam weakening and permeability increasing unit; performing weakening and permeability increasing on the next coal seam weakening and permeability increasing unit until the weakening and permeability increasing of a whole to-be-exploited coal seam are completed. The method has the advantages that presplitting is performed on deep coal surrounding high-pressure water injection holes, so that water injection influence radius is increased evidently, high-pressure water injection weakening speed is increased, and local coal stress concentration is avoided.

Description

technical field [0001] The invention relates to a coal seam weakening and anti-permeability method, in particular to a low-permeability coal seam weakening and anti-permeability method combined with pre-splitting and high-pressure water injection. Background technique [0002] Compared with the energy consumption structure of most countries in the world, coal occupies a particularly important position in China's energy consumption structure. In 2012 alone, China's raw coal output reached 3.65 billion tons, and coal consumption accounted for nearly 70% of the total energy. . As far as the coal resources that have been discovered in China so far, nearly half of them are buried below -1000m, and its total geological reserves are as high as about 3 trillion tons. At present, on the whole, China's coal resources are insufficient, and the coal resources in old mining areas are gradually shrinking. With the development of science and technology and the progress of human society, t...

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Problems solved by technology

Among them, deep hole loosening blasting, water jet slotting, and hydraulic punching technologies have problems such as small radius of influence, heavy workload, and relatively complicated construction, so they are not widely used in the field.

Coal seam water injection is an effective method for safety issues such as mine rock burst, coal and gas outburst, etc. At present, there is still a lack of comprehensive and systematic research, resulting in poor effect of coal seam water injection in coal mines in China; in addition, high pressure water is affected by the stress distribution of coal and The influence of the main cracks in the coal seam cannot control the direction of crack expansion. The local coal body is relieved, but the local coal body stress is concentrated; the uneven distribution of water space leads to an abnormal increase in local gas content and pressure, which becomes serious threat to safety; water injection pressure attenuation is serious, resulting in a small impact radius of water injection, a large amount of on-site construction, cracks appear "dense on the outside and sparse on the inside", resulting in poor sealing effect of drilling holes, difficulty in deep water injection during water injection, and water from the shallow working face The side flow phenomenon of the side of the lane

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